1. Field of the Invention
The present invention relates to a semiconductor device and an electronic apparatus mounting the same, more specifically relates to a semiconductor device in a packaged form which is small in size and high in integration density and an electronic apparatus mounting the same.
2. Description of the Related Art
In recent semiconductor devices such as very large sized integrated circuits (VLSIs), a 70% reduction of the size has been realized in three years and both higher integration and higher performance have been achieved. Along with this, package forms of semiconductor devices have also been made smaller and higher in density.
As forms of packages of semiconductor devices, dual in-line packages (DIP), pin grid arrays (PGA), and other through-hole mount device types (THD) wherein lead lines are inserted in through-holes formed on a printed substrate and quad flat (L-leaded) packages (QFP), tape carrier packages (TCP), and other surface mount device types (SMD) wherein lead lines are soldered on the surface of the substrate have been used. Further, there has been a shift to packages such as ball grid arrays (BGA) wherein the output terminals are arranged in two-dimensional areas.
On the other hand, demands for smaller sized and higher density semiconductor are still escalating and it is becoming impossible to meet the demands with the above QFP and other packages. Therefore, attention has been drawn to packages called chip size packages (CSP) which achieve even smaller and higher density semiconductor devices by making the size of the package as close as possible to a semiconductor chip. Considerable research is now underway and many proposals are being made.
In the above CSP, for example, as shown in the cross-sectional view of FIG. 1, a semiconductor chip 1 is mechanically and electrically connected to an interposer 2 at bumps 4. The area between the semiconductor chip 1 and the interposer 2 is filled with sealing resin 3. Terminals 5 formed in an array on the other side of the interposer 2 are electrically connected with the bumps 4 through through-holes 7 formed in the interposer 2. The terminals 5 are soldered as output terminals to a not-illustrated motherboard made from, for example, a glass epoxy based material.
In the above CSP, however, warpage sometimes occurs after the various heat processing steps in the manufacturing process. For example, when packaging a semiconductor chip of 10 mm square size, the coplanarity (maximum value of distance of terminal from plane when placing package on plane) reaches 30 xcexcm in some cases.
In order to prevent the above warpage, there is known a method to use an interposer made of a ceramic, however, the high price of ceramics becomes a factor in higher manufacturing costs and there is also a problem in durability and reliability. For example, in temperature cycle experiments giving 72 cycles of temperature change from xe2x88x9225 to 125xc2x0 C. a day, cracks (joint destruction) end up occurring at solder joint portions after about 100 cycles. Therefore, the durability is too short for practical use.
An object of the present invention is to provide a semiconductor device in a chip size package realizing a smaller size and higher density and having high durability and reliability and an electronic apparatus mounting the same.
To attain the above object, according to a first aspect of the present invention, there is provided a semiconductor device packaged and connected to a motherboard by soldering, comprising a semiconductor chip wherein a bump is formed on a pad portion thereof; an interposer supporting the bump mechanically and having a through-hole wherein a conductor is formed and connected to the bump electrically; and a sealing resin buried between the semiconductor chip and the interposer; the interposer being formed from a material having a glass transition temperature higher than a curing temperature of the sealing resin.
Here, the xe2x80x9cglass transition temperaturexe2x80x9d is the point where a material comprised of an organic material etc. changes from a hard glass-like state to a soft rubber-like state. Note that if this change occurs under pressure, it is impossible to maintain the hardness so deformation occurs.
According to the semiconductor device of the present invention, since the smaller size and higher density chip size package has an interposer formed from a material having a higher glass transition temperature than a curing temperature of the sealing resin, it is possible to carry out heat processing for curing the sealing resin at a lower temperature than the glass transition temperature of the interposer material. Therefore, it is possible to package a semiconductor device without such a glass transition of the interposer material, that is, without deforming the interposer. As a result, the durability and reliability can be improved.
According to a second aspect of the present invention, there is provided a semiconductor device packaged and connected to a motherboard, comprising a semiconductor chip wherein a bump is formed on a pad portion thereof; an interposer supporting the bump mechanically and having a through-hole wherein a conductor is formed and connected to the bump electrically; and a sealing resin buried between the semiconductor chip and the interposer; a coefficient of linear expansion of the interposer being a value substantially intermediate between those of the motherboard and the semiconductor chip.
According to the above semiconductor device, since the smaller size and higher density chip size package has a coefficient of linear expansion of the interposer of a value substantially between that of the motherboard and that of the semiconductor chip, it is possible to interfere with the stress caused by the difference between the expansion and contraction of the motherboard and the semiconductor chip in the heat processing steps in the manufacturing process or the difference between the expansion and contraction of the motherboard and the semiconductor chip caused by the heating of the device when used as a semiconductor device. As a result, joint destruction can be suppressed and durability and reliability can be improved.
According to a third aspect of the present invention, there is provided a semiconductor device packaged and connected to a motherboard, comprising a semiconductor chip wherein a bump is formed on a pad portion thereof; an interposer supporting the bump mechanically and having a through-hole wherein a conductor is formed and connected to the bump electrically; and a sealing resin buried between the semiconductor chip and the interposer; the interposer being formed from material having a bending strength of 400 MPa or more.
According to the above semiconductor device, since the smaller size and higher density chip size package has an interposer made from material having a bending strength of 400 MPa or more, it is possible to interfere with the stress caused by the difference between the expansion and contraction of the motherboard and the semiconductor chip caused by heating of the device when used as a semiconductor device. As a result, the durability and reliability can be improved.
Also, the semiconductor device of the present invention can improve the durability and reliability by combining the characteristics of the formation of the interposer by a material having a higher glass transition temperature than a curing temperature of sealing resin, the coefficient of linear expansion of the interposer being a value substantially intermediate between that of the motherboard and that of the semiconductor chip, and the interposer being made from a material having a bending strength of 400 MPa or more.
According to a fourth aspect of the present invention, there is provided an electronic apparatus comprising a motherboard on which an electrode is formed; a semiconductor chip wherein a bump is formed on the pad portion thereof; an interposer supporting the bump mechanically and having a through-hole wherein a conductor is formed and connected to the bump electrically; and a sealing resin buried between the semiconductor chip and the interposer; the interposer being formed from a material having a glass transition temperature higher than a curing temperature of the sealing resin; and the through-hole connected electrically to a corresponding electrode of the motherboard by solder.
Preferably, a coefficient of linear expansion of the interposer is of a value substantially intermediate between those of the motherboard and the semiconductor chip.
Preferably, the interposer is formed from a material having a bending strength of 400 MPa or more.
In the electronic apparatus of the present invention, since the interposer of the smaller size and higher density chip size package is formed by a material having a higher glass transition temperature than the curing temperature of the sealing resin, the heat processing for curing the sealing resin in the manufacturing process can be carried out at a lower temperature than the glass transition temperature of the interposer material. Namely, this electronic apparatus mounts a semiconductor device capable of being packaged without glass transition of the interposer material, that is, without deformation of the interposer, and therefore can be improved in durability and reliability.